A summary of outstanding problems

This brief presentation of some case histories of telescope projects illustrates how the state of the art in the engineering of astronomical observatories is not yet up to a knowledge level which should be required for designing reliably such complex systems.

The trials, errors and design corrections that we have briefly recalled above have been the consequence of missing knowledge on a number of still unclear and controversial issues related to the interaction of a telescope with wind, seeing and the local atmospheric turbulence, in particular:

• The relationship between the effects of dome and mirror seeing and the ventilation and temperature conditions of the telescope.

• The characterization of the high frequency wind (mechanical) turbulence acting on a telescope during the observations, which is the main responsible of guiding errors.

• The wind pressure field on the primary mirror and its relationship with optical aberrations.

• The effects of the atmospheric surface layer, which should influence in particular the choice of the height of the telescope pier.

1. To provide a larger and improved base of experimental data characterizing the atmospheric environment in several different types of telescope enclosures.

1. To obtain methods and figures for predicting the seeing and guiding performances of a telescope in relationship to the main variables that characterize the local atmospheric environment.

1. To contribute to the development of concurrent design approaches (see page ) aimed at bringing the process of designing telescopes and their enclosures on more rational bases than it has been the case in the past.

Thus our main aim will be to identify and characterize all the significant phenomena and establish parametric engineering relationships with the quantities which most influence them, sometimes at the price of simplifying approximations and generalizations.